The vascular endothelial function, which fails in the earliest period of arteriosclerosis, is expected in recent years to be used to diagnose cardiovascular diseases, diabetes, and other lifestyle diseases in their preclinical stages. In the most standard testing method used in worldwide clinical sites (flow-mediated dilation: FMD method), after a forearm is occluded for five minutes, the occlusion is removed to cause reactive hyperemia. An ultrasonic diagnosis device is then used to measure a flow-mediated dilation response, the intensity of which is maximized about one minute after reperfusion, to find a maximum increase ratio (% FMD) of the diameter of the brachial artery.
Further, evaluation of an increase in pulsation amplitude in reactive hyperemia (PAT ratio) by using a finger plethysmogram (evaluation of delay response after 90 seconds, which is a point of time later than post-reperfusion initial response assessed by using FMD method), is called peripheral artery tonometry testing (Endo-PAT method) which has been commercially available in Israel and increasingly used in clinical applications.
Further, as a device using the finger plethysmogram, there has been a proposed vascular endothelial function evaluation system including evaluation means for evaluating a vascular endothelial function level based on the difference between a pulse wave peak value and a pulse wave base value, evaluation means for evaluating the vascular endothelial function level based on the proportions of a reflected wave component (AI) to the systolic blood pressure of the pulse wave before occlusion of a forearm and after resumption of blood flow, evaluation means for evaluating the vascular endothelial function level by using a vascular aging index (AG) as a pulse wave characteristic value of the acceleration pulse wave, or any other means (Patent Literature 1).